Electric circuit interrupter of the plug-in type



A. clANcHl 2,416,569

ELECTRIC CIRCUIT INTERRUPTER OF THE PLUG-IN TYPE Feb. 25, 1947.

Filed Jan. 2, 1945 3 Sheets-Sheet l enlor lA/VC Hl 5;, BW A Attorneys A. CIANCHI Feb. 25, 1947.

ELECTRIC CIRCUIT INTERRUPTER OF THE PLUG-IN TYPE Fiied Jan. 2, 1943 5 Sheets-Sheet 2 F768@ WIK E F/GB. -L-

In ventor 14A/cm A A ttorneys A. clANcl-n 2,416,569

ELECTRIC CIRCUIT INTERRUPTER 0F THE PLUG-IN TYPE Feb. 25, 1947.

Filed Jan. 2, 1945 3 Sheets-Sheet 3 [Inventor .C1/)NCH l4 Attorney @A By Patented Feb. 25, 1947 ifi ELECTRIC CIBCUIT INTRRUPTER QF THE PLUG-IN TYPE Alfredo Cianchi, Hemel Hempsted, England Application January'v 2, 1943, serial No. 471,161

In (l-reat Britain December 2, 1941 This invention relates to an electric circuit interrupter such as switch or fusible cutout, of the plug-in type having relatively iixedA and movable portions bearing cooperating contact elements.

The invention has for its primary obje-ct to provide an improved practical construction of interrupter of this type in the form of a compact unit suitable for mounting either alone or in conjunction with other similar units in a ccniined space. the arrangement being 'such as greatly to simplify manufacture, and therefore also cost, without impairing the efficiency of operation of the nterrupter.

A more detailed object of the invention is to provide an improved plug-in type interrupter ernploving a mercury or other enclosed switch whose contact operation. is controlled by electromagnet external to the envelope of the switch, whei` in the parts are so arranged to facilitate inspection and maintenance and to ensure satisfactory operation. This object is achieved according to one feature of the invention by mounting the 'switch on the relatively movable portion of the interruptor and the electromagnet (or at least the main part thereof) on a separate member detachably mounted in a casing constituting the relatively fixed. portie-n of the vinterrupter, the arrangement being such that the act of plugging-in not only brings the main contacts into engagement but also brings the switch into the correct operative position in readiness for @nera-tion by the electromagnet.

A further object of the invention is to provide an improved plug-in tyne interrupter ernploying a fusible cut-out as its main interrupting element, wherein again the parts are so arranged as to facilitate inspection and maintenance, and more particularly to simplify replacement of the fuse element.

Another object of the invention is so to construct a plug-in type interruptor as to enable standard parts to be employed in the relatively iixed movable portions, either with an electromagnetically operated enclosed switch or with a fusible cut-out. as may be desired.

Yet another object of the invention is to provide improved main contact arrangements in a. plug-in type interruptor, which will minimise risk of damage to a mercury or other switch enclosed ina fragile envelope or of had contact engagement resulting from shock or vibration.

Still further objects of the invention will be apparent from the appended claims and from the v claims. (o1. 20o-112) 2 following description of the accompanying drawings, in which Figures 1, lc and lb together constitute an exploded view of a preferred construction according to the invention, Figure l being a vertical section on the line l-l of Figure 2, Figure la a side elevation of the detachable inner member, and Figure lb a vertical section on the line li-ll of Figure 6.-

Figures 2 and 3 are respectively a front view and a horizontal section on the line III-III of the iii/:ed casingv shown in Figure l,

Figure l is a front view of the detachable inner member shown in Figure la, the magnetic core being omitted,

Figure `5 is a vertical section through one half of the member shown in Figure 4,

Figure 6 is a back view of the movable cover shown in Figure 1b,

Figure 7 shows in plan the magnetic core belonging to the inner member shown in Figures 4 and 5,

Figures 8 and 8aA together constitute a partial exploded View or an alternative construction, Figure 8 showing the inner member in side elevation, whilst Figure 8a is a longitudinal section similar to that of Figure 1b through the cover,

Figure 9 is a horizontal lsection on the line IE5- IX of Figure 8o,

Figure l0 shows in vertical section similar to that of Figure 8d another modiiied Jform of cover,

Figure'll is a horizontal section on the line .XI-XI of Figure 10,

Figures l2 and 12o together constitute a partial exploded view, similar to that O f Figures 8 and 8d of a further alternative,

Figures 13 and 13o together constitute an exploded sectional view similar to that of Figures i, la and 17o of an arrangement employing a 4fusible cut-out,

Figure 14 is a front elevation of the cut-out member detached from the cover of Figure 13a,

and

Figures l5, 15a and 15b together constitute an exploded sectional view similar to that of Fgures 1, la and lb of yet another arrangement.

In the construction of Figures 1 to '7, the iiXed portion of the interrupter comprises a casing A of moulded or other insulating material in the form of narrow box of generally rectangular shape of suitable length and depth open at one of its edges. The casing is mounted with its length vertical and its open edge at the front.

Within the casing A near the top and bottom,

insulating barriers A1 are formed integral with the casing walls, thus providing small compartments within which the fixed contact elements are mounted. Each of these elements consists of a metal block B preferably with spring contact fingers B1 at its sides. Holes A2 are provided through the top and bottom walls of the casing for the connection of the two fixed contact elements tc the main circuit controlled by the interrupter.

The movable portion of the interrupter comprises a cover C of moulded or other insulating material so shaped as to form a handle which can be readily gripped by the fingers to facilitate plugging into and withdrawing from the xed portion, the cover being of a size to n1; over the open front of the xed casing A. Short insulat ing walls C1 project from the back of the cover to give protection for the fragile mercury switch D, which is housed within the trough thus formed at the back -of the cover. The movable contact elements which cooperate with the xed contact elements in the casing A are mounted at the top and bottom of the back of the cover C, and each consists of a pair of flat blades E engaging between the contact block B and the spring iingers B1 of the corresponding fixed contact element. This simple contact arrangement is adequate for cases where the interrupter has only to deal with 'relatively light currents and is not likely to be subject to vibration or shocks in use, the natural springiness of the contacts providing suflicient contact pressure and frictional grip for such cases, whilst yet permitting removal of the cover without shock likely to damage the mercury switch. A positive contact locking engagement may however be provided, as will be described later with reference to Figures 8 and 9, especially vin heavy current interrupters or interrupters liable to be subjected to vibration in use.

Each movable contact element is provided with ya terminal tting E1, to which can be attached one of the terminals D1 of the mercury switch D (or other switch) which constitutes the main member of the interrupter. Whilst other fastening means may be provided to hold the mercury switch in position, it will usually sufce to rely 'on the terminal attachments for this purpose, and it is preferable to provide some degree of flexibility in the mounting to prevent damage to the switch envelope during handling. In the example illustrated rubber buiier rings D3 are provided around the envelope in suitable positions,

the cover C and insulating walls C1 being slightly grooved to receive the edges of the rings D2.

The mercury switch D itself is of the type operated by an external electromagnet, and in the example shown has a plunger D3 of magnetic material within the envelope moved on energisation or deenergisation of the electromagnet to displace the mercury and thereby to make or break the circuit. Other forms of enclosed switch operated by an external electro-magnet may be employed, if desired. A small window C2 is preferably provided in the cover to permit the switch to be viewed from the front, so as to determine whether the circuit is open or closed. The electromagnet comprising a magnetic core F and a coil F1 is carried by an inner member G 'which is normally housed within the fixed casing A but is detachable therefrom. This inner member G consists of a framework of moulded or other insulating material shaped to t into the central compartment of the iixed casing A between the insulating barriers A1 and, iSV formed in two equal parts which fit together to form a closed nat box containing the coil F1, whose individual winding turns thus lie more or less in planes parallel to the length of the casing A. Cooperating studs and holes G1 serve to locate the two parts of the member G in their correct relative positions. The inner member G has a central rectangular opening G2, which registers with the central hole through the core F1 and through which the magnetic core F passes, the core being generally U-shaped (as above in Figure 7) with its base passing through the holes in the member G and in the core. The core is made up of .a stack of at laminations, each lying horizontally, and for ease of assembly, each lamination is formed in two parts, as indicated in Figure '7, one part being L-shaped and the other straight. By stacking these L-shaped and straight lamination parts alternately in two L-shaped stacks and forcing the two stacks into interleaved relationship within the central holes, a compact U-shaped core can be built up -to t snugly into the holes in proper position relatively to the coil F1, the free ends of the laminations adjacent to the pole pieces F3 being bolted together by pairs of bolts F2. The sides of the framework of the inner member G are recessed slightly at G3 for the reception of the inner edges of the core F, and the side walls of the casing A are shaped to afford recesses A3 for accommodating the parts of the core projecting from the sides of the inner member G. When the complete inner member is inserted in the casing A and the cover C is plugged into the casing, the pole pieces F3 come close one on either sid-e of the mercury switch D in proper position for the operation thereof` when the coil is energised.

At its lower end, the framework G has two grooves G4 for the reception of metal terminal bars H, and a deep slot G5 is cut through in each half from the central compartment housing the coil F1 to the corresponding groove G4 for the passage of the leads from the two ends of the coil to the two bars H. One of these leads passes direct from the coil to the terminal bar, the necessary Contact being obtained by folding the wire along the base of the groove and then clamping the terminal bar down tightly against the end of the wire. The other lead from the coil is taken to one of a pair of spring clips H1 tted into the inner member G near the top, these clips serving to hold a small fuse H2 in a compartment G6 at the top of the member. The other spring clip H1 is connected by a lead passing through the interior of the member to the sec ond terminal bar H. The coil F1 is thus connected in series with the fuse H2 between the two terminal bars H. The purpose of this small fuse H2 is to prevent damage to the mercury switch D resulting from the flow of excessive current through the coil F1, due for instance to inadvertent connection of the coil terminals to an incorrect voltage supply. The inner member G is preferably provided with a pocket (not shown) for the reception of a spare fuse.

The iixed casing A is provided with pairs of holes, which can be alternatively used for the external connections to the coil terminal bars-H in accordance with convenience. Thus one pair of holes A4 is provided in the bottom end wall of the casing, and another pair A5 in the back wall, whilst the two holes of a third pair A@ pass respectively through the two side walls of the casing, this third pair being especially convenient for instances in which two or more interrupte's agresse are mounted side by side with their coils con-- nected in series with one another for simultaneous operation of all the mercury switches, .as for example on polyphase circuits having one switch in each phase.

The inner member G and the interior or" the casing A are preferably so shaped as to prevent the member from being inserted the wrong way round in the casing, that is with the coil terminals H at the top and the fuse H2 at the bottom. Similarly the cover C is provided at one end only with a small stud C3 which nts within a recess A" in the casing wall, thus preventing the cover from being plugged in upside down. Recesses A are formed in suitable positions in the casing Vwalls to give clearance for the switch terminal connections D1 and terminal ttings El.

As mentioned above, it is .sometimes desirable to provide means for locking the main Vcontacts closed, for eXampl-efto ensure good contact enc gagement in heavy current installations or to prevent accidental loosening of the contacts in cases when the interrupter is subjected to vibration or t0 severe shocks, and one convenient arrangement for this purpose is illustrated in Figures 8 and 9, which also serve to show a further variant in whch the magnetic circuit of the electromagnet is in two parts 'respectively on the fixed and movable portions of the interrup'ter. Figure 8 shows 'an exploded View of this arrangement, analogous to that of Figure l, but the xed casing is omitted from the drawing since it is identical with that shown in Figure l.

In 'this arrangement each movable contact element on the cover C consists oi a at strip J i bent into the form of aU so as to form two blades engaging between the 'contact block B and the spring ringers B1 ofthe fixed contact element, the strip J being fairly rigid with only relatively slight ilexibility. The element is attached to the cover C by means of a screwthreaded bolt J1 engaging in a tapped hole in the base of the U, this bolt having a small hand lever J2 in front of the cover C to facilitate tightening and loosening as required. The two corner edges of the base of the U bed against upstanding knife edges J3 on a small metal plate J4 disposed on the back face of the cover C, and it will be clear that with this arrangement tightening of the bolt J1 will deform the element J so as to force the free ends of the limbs of the U towards one another and into tight engagement with the 'xed contact block B, whilst loosening will allow them to open out to their naturel parallel position.

The two small hand levers .32 are operated to loosen the bolts J1 when it is desired to `withdraw the movable portion from the iixed portion, and they may be so mounted vthat the act of gripping the main handle of the cover itself operates them to effect loosening of the bolts, the bolts being likewise left loose for the operation of .plugging-in. The fixed contact elements on the fixed portion are so arranged that so long as the bolts J1 are loose and the moving contact blades J are in their natural parallel position the movable portion can be' readily and easily pluggedin and withdrawn without shock. The small hand levers J2 are however operated to tighten the bolts J1, when the movable portion has been plugged in. so as to force the two blades J of each movable contact element towards one an- 4other and thereby to cause them to exert a locking pressure against the contact block B of the fixed contact element. In this way the movable portion is frlctionally locked in its plugged-in position, and good electrical contact ensured. If desired, the two blades `J of each movable contact element and the cooperating parts of the x'ed 4contact element may have ribbed or roughened surfaces or may be slightly curved or bent to provide a positive locking action when the locking bolt J1 is tightened without relying wholly on friction. This arrangement thus allows good electrical contact to be obtained, whilst still permitting free and easy removal of the lmovable portion when desired.

The inner member G is arranged exactly as in the construction of Figures l to 7, except that the magnetic core of the electromagnet is divided with its pole pieces carried by the cover C and only the main Ll-shaped part of the core carried by the inner member G. T us the limbs of the main part K of the core are shorter and carry pairs of spring 'blades K1 of magnetic material which make Contact with the pole pieces K2, these pole pieces being secured to the ycover C in their proper operative positions relative to the mercury switch D. Thus on plugging the ycover C into the fixed casing A, the main electrical circuit is completed at the contacts and at the same time the magnetic circuit of the electromagnet is completed by engagement of the blades K1 with the pole pieces K2.

Figures l0 and 11 show a modification in the mounting of the mercury switch D on the cover between the insulating walls C1 at the back thereof, in order to relieve the switch more effectively from risk of damage due to shocks. In this modification the switch is provided at it ends with metal terminal caps L, which are connected by exible leads L1 to the electrical terminals of the switch and also by light springs L2 to the ends of the envelope. Protective sheaths L3 of insulating material are provided which nt over the ends of the envelope and may if desired extend for the whole length of the envelope, and these sheaths act as guides to limit the movements of the metal terminal caps L relatively to the envelope. The terminal caps L themselves constitute the connections from the switch to the main conta ct `elements on the cover and various alternative clamp-ing arrangements may be provided to ensure proper contact engagement between the caps and the elements'. In the example illustrated the Contact elements L4 are made Ueshaped with the base of the U of saddle shape. so that the terminal caps L are held between such saddles and the main body of the cover C to which the Contact elements are attached.

The switch carried by the cover may be of the latch-in type, that is of the type in which the switch when once closed by the energisation of the electromagnet is held latched in the closed position after the electromagnet has been deenergised, a separate tripping electromagnet being provided for releasing the latch and opening the switch. Figure 12 shows the cover and inner member for such an arrangement, these parts cooperating with a fixed casing of the kind shown in Figuresl l to 3. In this arrangement, the cover C is arranged in the manner described above. except that the switch D itself is in this instance of the latch-in type.` The inner meno:- ber differs from that above described in that there are two electromagnets, two sets of terminals and two fuses instead of one. Thus the inner member consists of a moulded framework M iormed in two parts which fit together to form a central compartment housing a closing coil N and a tripping coil O, the two coils being located .terminal bars N3 or O3.

Figure 7. At each end of the framework, there are a small compartment containing a fuse N2 newal of the fuse wire, when necessary can then or O2 and also a pair of grooves M2 for holding Thus one lead from the closing coil N passes to the fuse N2 and thence to one of the two terminal bars N3, whilst the other lead from the coil N goes to the other terminal bar N3, with similar connections from the tripping coil O at the other end. The arrangement of these parts will be clear from the description already given with reference to Figures l1 to 7. The fixed casing A is bored with addi- -itional holes A4 or A5 or A6 at its other end for the circuit connections from the additional electromagnet.

With such an arrangement (as also sometimes with the other arrangement) it is desirable to provide an interlocking device (not shown) to prevent the cover C from being withdrawn from the casing A except when the switch is open. Such device may consist of a sliding bolt which is moved to its latching position when the closing coil is energised and to its open position when the -tripping coil is energised. In some instances it may also be desirable to provide a short-circuited winding on each pole of the electromagnet core vor cores in the well-known manner to prevent chattering.

The main member of the interrupter, instead of being in the form of a mercury or other en closed switch, may consist of a fusible cut-out connected between the movable contact elements, and it is especially convenient for the fixed casing A and the movable cover C to be of such construction that they can be employed, at will, either with a switch as above described or with a fusible cut-out, the inner member used in the case oi" the switch being removed in the latter event and the space thus vacated occupied by a fitting containing the cut-out and a magazine lfor the renewal of the fuse link of the cut-out.

Figures 13 and i4 show the interrupter of Figures 1 to Z adapted for use with a cut-out. In this arrangement the xed casing A yand the cover C are identical with the corresponding parts of the arrangement of Figures i to 7, but 'the inner member G and the mercury switch D are replaced by a two-part moulded fitting P which ts between the insulating walls Cl of the cover and is suitably anchored thereto. This fitting P contains two compartments, one of which P1 contains a reel P2 rotatably mounted on a pivot pin P3 mounted in the fitting. This reel P2 has fuse wire wound on it to constitute a magazine for the renewal of the fuse link, the wire from the reel passing out from the magazine chamber through a small end hole P4. The second compartment P is of stepped cylindrical construction and houses concentric cylinders of i refractory insulating material through which the fuse-link passes. Thus the fuse-link may consist o-f a length of the wire already drawn off the magazine reel P2, passing through a tube Pi of asbestos within an outer steatite tube P7, the.

free end of the fuse wire being attached to the terminal iitting E1 on one of the contact elements whilst the part of the wire leading from the fuse to the magazine reel is looped around the other `'terminal fitting E1 and clampedV thereby. Re-

be effected very simply by pulling out a suitable length of wire from the reel and attaching a loop of it and also its free end to the two terminals E1.

In cases where it is preferred to employ a cartridge fuse, the magazine chamber P1 can contain 'one or more spare fuses instead of the magazine Figure 15 shows a further variant in which the main member of the interrupter comprises a mercury switch Q and a fusible cut-out in series, the latter being mounted in a fitting Q1 arranged in the manner just described with reference to Figures 13 to 14. The xed casing A 'and cover C are each made long enough to accommodate the switch and cut-out one above the other, but otherwise are arranged generally in the manner above described, the cover carrying an intermediate-terminal block Q2 through which the switch and cut-out are connected together.

What I claim as my invention and desire to secure by Letters Patent is:

1. An electric circuit interrupter of the plug-in type, including in combination a relatively fixed casing of generally rectangular shape, relatively fixed contact elements mounted on the casing near its ends, an inner member detachably mounted within the casing between such contact elements, an electromagnet having a coil and a core at' least the main part of which is carried by the'inner member, a cover movable relatively to the casing, relatively movable contact elements cooperating with the relatively fixed contact elements and carried by the cover near its ends,

and an enclosed switch housed within the cover between the relatively movable contact elements and having its terminals connected to such elements, the arrangement being such that when the two relative portions are plugged together with the cooperating contact elements in engagement the switch is connected in circuit through the contacts and is brought into operative relationship with the electromagnet core. contact operation of the switch being controlled by the electromagnet.

2. An electric circuit interrupter, as claimed in claim 1, in which the magnetic core of the electromagnet is generally U-shaped with its plane transverse to the length of the casing when the inner member is in position therein, whilst the coil extends around the base of the U with its plane longitudinal with respect to the casing.

3. An electric circuit interrupter as claimed in claim 1, in which the inner member comprises a compartment housing the electromagnet coil, terminals at at least one end of the member, and means for connecting the ends of the coil to such terminals, and the relatively fixed casing is provided with an insulating barrier for separating such terminals from the relatively xed contact elements.

4. An electric circuit interrupter as claimed in claim 1, in which the inner member comprises a box-like insulating framework formed in two interfiting parts and containing the electromagnet coil within it, means for supporting the electromagnet core, such core being generally U-shaped with its base passing through the coll only be inserted into the casing in one way with its terminals always lying at the same end of the casing and insulated from the relatively xed contact element at such end of the casing.

5. An electric circuit interrupter of the plug-in type, including in combination a relatively xed casing of generally rectangular shape, relatively fixed contact elements mounted on the casing near its ends, an electromagnet housed within the casing and having a generally U-shaped magnetic core with its plane transverse to the length of the casing and a coil extending round the base of the U with its plane longitudinal with respect to the casing, a cover movable relatively to the casing, relatively movable contact elements cooperating with the relatively fixed contact elements and carried by the cover near its ends, and a mercury switch housed within the cover between the relatively movable contact elements and having its terminals connected to such elements, the arrangement being such that when the two relative portions are plugged together with the cooperating contact elements in engagement the switch is connected in circuit through the contacts and is brought into operative relationship with the electromagnet core, contact operation of the switch being controlled by the electromagnet.

6, An electric circuit interrupter of the plug-in type, including in combination a relatively fixed casing of generally rectangular shape, relatively fixed contact elements mounted near the ends thereof, a cover movable relatively to the casing, relatively movable contact elements cooperating with the relatively xed contact elements and carried by the cover near its ends, and a main circuit interrupting device carried by the cover and connected between the relatively movable Contact elements, at least one of the relatively movable contact elements consisting of a at strip bent into the form of a U, a pair of knife edges against which the base of the U-shaped strip abuts, and a clamping device which acts on the base of the strip between the knife edges and when operated forces the base more tightly into engagement with the knife edges and thereby causes the limbs of the U to exert a gripping pressure on the relatively xed Contact element engaging between such limbs.

7. An electric circuit interrupter as claimed in claim 1, in which each of the relatively movable contact elements consists of a flat strip bent into the form of a U, a pair of knife edges against which the base of the U-shaped strip abuts, and a clamping device which acts on the base of the strip between the knife edges and when operated forces the base more tightly into engagement with the knife edges and thereby causes the limbs of the U to exert a gripping pressure on the relatively xed contact element engaging between such limbs.

ALFREDO CIANCHI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,461,038 Keyes July 10, 1923 Re. 22,266 Adam et al Feb. 16, 1943 1,628,802 Perrem May 17, 1927 2,024,216 Grady Dec. 17, 1935 1,130,485 Davis Mar. 2, 1915 1,947,503 Shunk Feb. 20, 1934 2,298,053 Helland Oct. 6, 1942 1,656,800 Turenne Jan. 17, 1928 FOREIGN PATENTS Number Country Date 61,171 Norwegian July 24, 1939 21,914 Netherlands Apr. 17, 1930 

